Heliocentrism and Geocentrism

The difference between an easy model and a complicated one.
Click in the canvas to erase the orbits!

Timeline

Timeline

≈ 350 BC, Aristotle

Aristotle, a pupil of Plato, becomes the tutor of Alexander the Great.
Aristotle's views of the world shape science for centuries. His influence lasts
until the enlightenment. In his book On the Heavens (part 14),
Aristotle asserts
that:

From these considerations then it is clear that the earth
does not move and does not lie elsewhere than at the centre.

≈ 250 BC, Aristarchus

Aristarchus estimates the size of the sun to be much larger than the
size of the earth. Based on this observation he then presents the heliocentric model.

In his book Almagest,
Ptolemy introduces so called epicycles to explain planetary motions,
based on the assumption that the earth is at the centre and does
not move. Almagest is considered to be one of the most influential scientific works in history.

Tycho Brahe observes a star being born and publishes his observation
in De nova stella. Brahe's observation refutes the commonly held view
at the time,
a view which dates back to Aristotle, that the stars are fix and never changing at the outskirts of the universe. Since Brahe couldn't observe
a stellar parallax, he concluded that the earth did not move. He proposed a model where the planets move around the sun, and the sun moves
around the earth. (It was later shown that it wasn't a star being born Brahe had
observed, but the supernova SN 1572, i.e. a star exploding.)

1609, Johannes Kepler

Using the observational data collected by Tycho Brahe, Johannes Kepler introduces his
first two laws of planetary motion in Astronomia nova. The first law:
the planets move in elliptical orbits with the sun at one focus.

Thanks to his intuition as a brilliant physicist and by relying on different arguments,
Galileo, who practically invented the experimental method, understood why only the sun could function as the centre of the world,
as it was then known, that is to say, as a planetary system. The error of the theologians of the time, when they maintained the
centrality of the earth, was to think that our understanding of the physical world's structure was, in some way, imposed by the
literal sense of Sacred Scripture.